Mobile swivel ladder

ABSTRACT

A rescue mobile ladder comprising a ladder pivotally connected at one end to a vehicle and a cage pivotally suspended on the second end of the said ladder so that under the action of gravity, said cage adapts itself automatically to any change in the incline of the ladder relative to the horizontal position.

United States Patent [72] Inventors Willi Siefermann, deceased late of Bussardweg 49, Karlsruhe, Germany by Luise Siefermann, nee Gaugler, executrix;

Dorothea Siefermann, Bussardweg 49, Karlsruhe; Hans Sielermann, Kreuzstr. 12, Forchheim near Karlsruhe, both of Germany [21] Appl. No. 812,540 [22] Filed Mar. 10, 1969 [45] Patented Dec. 7, 1971 [32] Priority Mar. 14, 1968 [33] Germany I [31] Pl708079.4

[54] MOBILE SWIVEL LADDER 12 Claims, 6 Drawing Figs.

[52] U.S.Cl 182/66,

[51] lnt.Cl E06c 5/06, B661 1 1/04 [50] Field olsearch l82/2,65, 66, 67

[ 56] References Cited UNITED STATES PATENTS 3,078,949 2/1963 Hoard 182/2 3,258,084 6/1966 Robb 182/2 Primary Examiner- Reinaldo P. Machado Attorney-McGlew and Toren ABSTRACT: A rescue mobile ladder comprising a ladder pivotally connected at one end to a vehicle and a cage pivotally suspended on the second end of the said ladder so that under the action of gravity, said cage adapts itself automatically to any change in the incline of the ladder relative to the horizontal position.

MOBILE SWIVEL LADDER A rescue mobile ladder comprising a ladder pivotally connected at one end to a vehicle and a cage pivotally suspended on the second end of said ladder so that under the action of gravity, said cage adapts itself automatically to any changein the incline of the ladder relative to the horizontal position.

This invention concerns a mobile swivel ladder comprising a ladder assembly pivotably connected to a revolving turret pivotable relative to the vehicle about an axis perpendicular to the longitudinal axis of the vehicle, for swiveling in a vertical plane, it particularly concerns those ladders which are selfpropelling or motor driven.

As is well known, swivel ladders serves as fire escapes for rescuing people in a disaster. Conventional swivel ladder constructions only permit rescue actions from places which are situated above or at the horizontal position of the ladder assembly. These conventional swivel ladder constructions do not permit the rescuing of persons, however, who are at a place located below the horizontal position of the ladder assembly.

It has become apparent, however, in several cases in which swivel ladders are used, particularly those in the fire service that it is necessary to rescue persons from a place of danger on a level with the ground and to bring them to the point where the swivel ladder is erected by means of a bridge formed by the extended ladder, the place of danger being separated from the point where the ladder is erected by water, an excavation, a mound of earth or the like. Even more frequent are cases in which it is necessary to rescue nonswimmers from open water or collapsed people from icy water. In all these cases of use it has hitherto been necessary, when using conventional swivel ladder constructions, for the ladder assembly to be first extended in a horizontal position, swiveled relatively to the vertical swivel axis of the revolving turret, then the ladder has to be traversed by a rescuer and a rope or a rope ladder or the like rescue appliance mounted by the rescuer at the end of the ladder and let down to the ground or into the water. Due to the necessity of dealing with a rope ladder or a similar means of rescue at the end of the ladder valuable time is lost in preparation, particularly when the success of the rescue operation depends on speed, the time including that necessary to bring the swivel ladder into its final position of use.

The object of the present invention is to provide a mobile swivel ladder which avoids the disadvantages of conventional swivel ladder constructions and, without restricting its possibilities of use for rapid rescue of persons located at the level of the horizontal position of the ladder assembly or places above it, also permits the rescue of people located in places below the horizontal position of the ladder assembly without loss of time. At the same time, the rescue of people without the use of other means is made possible solely by means of the ladder assembly, which can be lowered and extended to a varying degree.

According to the present invention a mobile, more particularly self-propelling or motor-driven swivel ladder, comprises a ladder assembly linked to a revolving turret for swiveling in a vertical plane, said turret being pivotable relatively to the vehicle about an axis perpendicular to the longitudinal axis of the vehicle; the ladder assembly is also pivotable about an angle measured downwardly from the horizontal in the plane including the axis of rotation of the revolving turret and the longitudinal axis of the vehicle.

The swivel ladder is merely lowered and extended accordingly. in particular, in saving lives over existing fences or walls, it may be advisable to provide a suspended cage at the top of the swivel ladder. The use of the swivel ladder according to the invention, comprising such a cage, is readily possible. Such a suspended cage makes it possible to effect rescues not only over obstacles which prevent any further lowering of the ladder, but also to rescue persons from chasms, pits or the like, since the suspended cage provided on the lowered ladder can be introduced into the depression. On the other hand, a swivel ladder according to the invention also enables the use of a new type of upright cage positively controlled with regard to the angle of incline of its base or platform relative to the axis of the ladder. Such a swivel ladder is particularly suitable for rescuing persons in difficulties in open or icy water since the upright cage can be brought just above the surface of the water, a rescuer being already stationed in the cage during the swiveling and extension of the ladder assembly so as to be immediately available as soon as the site of the accident is reached, to help the person in difficulty into the cage.

In a preferred embodiment of the invention the ladder assembly is pivotable at least through such a negative angle relatively to the horizontal, that in its extended condition the end of the ladder can be reached and the ladder climbed from the ground. In another embodiment of the invention in which the ladder assembly is pivotable about such a negative angle relatively to the horizontal, in the retracted condition of the ladder, the end can be reached from the bottom of the ladder.

The apparatus for swinging the ladder assembly in a vertical direction, i.e., the erecting device, can be constructed in any known manner. In the majority of cases it has proved to be advisable to provide one or two hydraulic cylinders as means of erecting the ladder assembly. In the case of such a swivel ladder having at least one hydraulic cylinder as means of swiveling the ladder assembly in a vertical direction, it has proved to be particularly suitable for the action of the erecting cylinder or cylinders at the revolving turret end to take place in the direction of the longitudinal axis of the vehicle and/or at such a space from the lower limiting plane of the revolving turret that the center axis or axes of the erecting cylinder or cylinders subtends or subtend an angle in a range between 30 and 50 in the maximum lowered position of the ladder assembly relative to the horizontal, with respect to the lower limiting plane of the revolving turret.

Alternatively or in addition other features have proved to be suitable in the construction of the swivel ladder. A further embodiment of the invention is that the base of the erecting cylinder or cylinders at the mounting end is at such a distance from the swivel axis for the relative swiveling of mount and revolving turret, that the center axis or axes of the erecting cylinder or cylinders subtends or subtend an angle between 30 and 50 with the lower limiting plane of the revolving turret relative to the horizontal, in the maximum lowered position of the ladder assembly.

In the embodiments of the invention comprising hydraulic cylinders as erecting means, the connection of the erecting cylinder or cylinders at the base end may be formed as a ball and socket joint. ln this embodiment of the invention it has proved to be advantageous if the receiving device provided on the mount and intended for the pressure cap of the connection at the mount end, formed as a ball joint is shortened at its end facing the connection at the revolving turret end of the associated erecting cylinder and if furthermore, this receiving flange is arranged at such an angle relative to the upper surface of the mount that its end facing the connection of the associated erecting cylinder at the revolving turret end extends approximately into the base plate of the receiving device for the pressure cup, secured to the mount.

According to another feature of the invention, the connection at the revolving turret end and/or the mount end, may have a different construction. According to this embodiment of the invention, at least one connection of the erecting cylinder or cylinders may be constructed as an ordinary swivel bearing, the concave cap of which is secured to the erecting cylinder or its piston rod and the convex cap of which is journaled to pivot about an axis parallel to the axis of the relative swiveling of mount and revolving turret, it center bearing being journaled to pivot on the revolving turret or the mount about an axis parallel to the axis of relative swiveling of mount and revolving turret.

in a swivel ladder of the present invention comprising a mount formed from metal plates connected in the manner of building blocks, the end of the mount remote from the swivel connection of mount and revolving turret may have a recess for receiving the erecting cylinder or cylinders in the lowered position of the ladder assembly relative to the horizontal. It has become apparent that the resistance to twisting of a mount formed in such a manner can be kept constant or even increased relative to that of a conventional mount without a cutout end surface as used on conventional swivel ladders which are not capable of being lowered below the horizontal; this is because the end of the mount remote from the swivel connection of mount and the revolving turret is connected by means of a partition wall located near the upper edge of its recess, to the upper top wall of the mount; this partition is at such an angle relatively to the upper wall of the mount that, when the ladder assembly is in its maximum lowered position relative to the horizontal, it assumes a position approximately parallel to the upper surface of the erecting cylinder or cylinders.

Swivel ladders comprising a mount and not capable of being lowered relatively to the horizontal are already known, and are provided with a device for receiving the mount on the revolving turret in the maximum lowered position. According to a further feature of the invention, in a swivel ladder which is constructed according to the present invention for lowering below the horizontal, this device for receiving the mount on the revolving turret may be utilized in the maximum lowered position to relieve the erecting device, particularly when constructed with hydraulic cylinders, and in the maximum lowered position, when there is a comparatively unfavorable division of the torque components in respect of the connection of the mount and revolving turret, it is used also to define exactly the maximum lowered position, which is a particular advantage when it is necessary to bring the ladder assembly as rapidly as possible accurately into this maximum lowered position, more particularly if the receiving device is constructed and arranged so that it comes into action only when the maximum lowered position of the ladder assembly is reached. This can be achieved if the receiving device is formed as a projection arranged on a sidewall of the mount, with a lower face which can be brought into contact with a contact surface of the revolving turret, the lower surface of each projection being bevelled so that when the ladder assembly reaches its maximum lowered position it comes snugly into contact with the associated contact surface of the revolving turret.

The present invention provides a flexible means of rescue in a disaster, which means was not achievable with conventional appliances, and renders possible, without loss of erecting time, the rescue of persons across a space of water or from open or icy waters even if the place where the person to be rescued is located is below the horizontal plane including the horizontal position of the ladder assembly. In accordance with other embodiments of the invention, such a swivel ladder may even be constructed so that its vehicle is higher than the place where the person to be rescued is located, such as, e.g., the case may be in rescuing persons, particularly injured persons, from a dyke or quayside.

The features which have been described above may be used individually or in combination with each other.

The present invention is described hereinafter with reference to several embodiments illustrated in the drawings in which:

FIG. I is a side view of a swivel ladder which is selfpropelling and motor driven, and comprises a ladder assembly connected to a revolving turret pivotable relatively to the vehicle about an axis perpendicular to the longitudinal axis of the vehicle, for swiveling in a vertical plane, four ladder positions being shown schematically, i.e., a lowered position with lowering of the ladder assembly through a negative angle relative to the horizontal, a lowered or horizontal position, an intermediate position with an angle of approximately 30 relative to the horizontal, and a position corresponding approxi mately to the maximum incline, there being a suspended cage maintained vertical irrespective of the incline of the ladder.

FIG. 2 shows the swivel ladder according to FIG. I in a view corresponding to FIG. I, said ladder, however, having an upright cage at its end irrespective of the angle of the ladder.

FIG. 3 is a perspective view on a magnified scale of details of the revolving turret and mount of the swivel ladder of the present invention in its maximum lowered position.

FIG. 4 shows, on a magnified scale, a side view of a revolving turret and mount according to FIG. 3 seen in the direction of the arrow A, the connection at the revolving turret and mount ends of the apparatus being constructed as a hydraulic cylinder for swiveling the ladder assembly in a vertical direction with a ball and socket joint:

FIG. 5a is a section in a plane parallel to the vertical plane including the longitudinal axis of the vehicle and the axis of rotation of the revolving turret of a hydraulic cylinder mounting, on a magnified scale: and FIG. 5b is a view of FIG. 5a seen in the direction of the arrow B.

In the swivel ladder shown in FIGS. 1 and 2, l is the chassis of the ladder, 3, a revolving turret, 2, a ladder assembly comprising the ladder sections 3a, 3b, 3c, 3d, and 6 shows a general drive for the swivel movement of the ladder assembly in a vertical direction. A lowered position 3,, of the ladder assembly is shown in full lines and the horizontal position 3, thereof in chain dotted lines; there is an intermediate position of the ladder assembly shown at 30 and another at an angle of approximately being the position of maximum incline of the ladderin the case shown it is in its retracted condition.

The position of the ladder for negative incline is indicated by 3,, the horizontal position by 3, and the two positions illustrated for positive incline by 3,, and 3, In the intermediate position 3 with an approximately 30 positive incline, the ladder assembly 3 is shown in the extended condition in which its individual ladder sections 3a, 3b, 3c, 3d, are shown, while the ladder assembly is shown in its retracted condition in all the other positions. In FIG. 2, the ladder assembly 3 is shown in a partly extended condition, even in the position 3,, with a negative incline relatively to the horizontal.

In FIG. 1 a suspended cage 8 is arranged at the top 3d of the ladder by means of a holding device 9 formed as a transfer ladder so that, under the action of gravity, the cage adapts itself automatically to any change in the incline of the ladder relative to the horizontal so that its base platform 4 always assumes a horizontal position.

In FIG. 2 an upright cage 5 is arranged at the top 3d of the ladder, a short mounting ladder 5' extending to the surface of the ground being provided at the front of the cage. The cage is positively controlled by means of a device (not shown) so that, upon a change in the incline of the ladder relative to the horizontal, its base platform 4 always maintains a horizontal position.

In FIGS. 1 and 2 the connection at the revolving turret end is indicated by the FIG. 12 and the connection at the mount end by 15, said connection being associated with the erecting device 6 formed as a hydraulic cylinder. In addition, the mount is indicated by 7 and is connected to the revolving turret 2 to pivot about the swivel axis 16.

In FIG. 3 the revolving turret and mount unit is shown in a magnified perspective view. The erecting device 6 has two hydraulic cylinders 13a, 13b, with cylinder axes 13a and 13b. The mount 7, which is connected to the revolving turret 2 to pivot about the swivel axis 16, has an upper cover surface 70', and a contact device 24 formed as a U-section 24' welded to its longitudinal surfaces (not shown), with an inclined lower edge 24"only one U-section 24' being shown-which, upon reaching the maximum lowered position 3,, takes the weight of the ladder off the hydraulic cylinders 13a, 13b, and defines the maximum lowered position 3,, where the inclined lower edge 24" of the U-section 24' located on the inclined upper edge 2 of the revolving turret 2 provided for the purpose and thereby supports the mount 7 on revolving turret 2.

The front end 7" of the mount 7 has a recess 22 in order to make it possible for the mount, which is Welded from sheet metal members to be lowered by the hydraulic cylinders 13a, 13b, freely through a sufficient negative angle relative to the horizontal.

The revolving turret and mount unit according to FIG. 3 is shown in FIG. 4 in side elevation seen in the direction of the arrow A in FIG. 3, in full lines in the maximum lowered position of the mount 7 and in chain dotted lines in the maximum erected position of the mount. A hydraulic cylinder, indicated in general by 13 and the cylinder axis of which is indicated by 13' is also shown in full lines for the maximum lowered position and in chain dotted lines for the maximum raised position. The lowered position of the mount is indicated by 7,,.

The connection of the cylinder at the revolving turret end is indicated by 12 and the connection of the piston rod 14 at the mount end is indicated by 15. Both connections 12 and 15 are formed as ball and socket joints. The receiving device 17 provided on the mount 7 and intended for the pressure cap (not shown) of the connection 15 on the mount end is shortened at its end 17v facing the connection 12 at the revolving turret end, approximately as far as the edge of the receiving flange 17a for the pressure cap, and this receiving flange 17a has such an incline 'y relatively to the upper mount surface 7' that its end 17v facing the revolving turret end connection l2-the front endextends approximately into the base plate 17b of the receiving device 17 for the pressure cap, mounted on the mount 7. In a preferred embodiment of the invention, the angle -y amounts to approximately 18. The connection of the cylinder 13 at the turret end may be formed similarly to the connection 15 of the piston rod 14 at the mount end and in particular has the same incline of the receiving flange for the pressure cap of the receiving device.

The connection 12 of the cylinder 13 at the turret end is constructed so that its axis of rotation, which corresponds to the center of the ball of the ball socket joint 12, is at such a distance a from the axis of rotation of the revolving turret in the direction of the longitudinal axis of the vehicle, shown by 11 in FIG. 3, and is at such a space b from the lower limiting plane 2' of the revolving turret 2 that the center axis 13' of the hydraulic 13 includes, in a maximum lowered position 3 (shown in full lines in FIG. 4) of the ladder assembly an angle B in a range of 30-50 with the lower limiting plane 2' of the revolving turret 2. In a preferred embodiment of the invention, the distance a is 325' mm. the space b 67 mm. and the angle B, with maximum lowered position of the mount 7 (corresponding to a maximum lowered position 3 of the ladder as sembly 3) 32. The maximum lowered angle a relative to the horizontal is 8 The connection 15 at the mount end is provided at a space 0 from the swivel axis 16 for the relative swiveling of mount 7 and revolving turret 2 and a free length 1 of the piston rod 14 in the retracted condition (corresponding to maximum lowered position) is selected so that the center axis 13' of the hydraulic cylinder 13, with maximum lowered position 7,, of the mount 7 (corresponding to maximum lowered position 3,, of the ladder assembly 3) encloses an angle B between 30 and 50 relative to the horizontal with the lower limiting plane 2' of the revolving turret 2, This angle [3 is 32 for a preferred embodiment, while the free piston rod length between the upper edge of the cylinder 13 and center of the pressure ball of the bearing 17 at the mount end supported by the piston rod 14 is approximately 85 mm. The distance 0 is approximately 700 mm.

In FIG. 4 a partition 23 is also shown in broken lines which is formed by a plate welded along the front 7" of the mount 7 approximately near the upper edge of its recess 22 and with its other end welded to the upper cover wall 7' of the mount 7 so that it has such an incline 8 relative to the upper cover wall 7 of the mount 7 that, in the maximum lowered position 7,, of the mount (corresponding to maximum lowered position 3,, of the ladder assembly 3) relative to the horizontal, it assumes a position approximately parallel to the upper generating line of the hydraulic cylinder 13. The angle 8 is preferably 24.

In FIGS. 5a and 5b another embodiment of the connection of the hydraulic cylinder 13 at the turret end is shown. In this embodiment an ordinary swivel bearing is used which is cheaper than the ball and socket joint connections according to FIG. 4 There is a pin 21 in bearing lugs 25a 25b of a bearing stand 25 welded at a suitable place on the revolving turret 2, mounted to pivot so that its axis 20 assumes a position at right angles to the plane including the longitudinal axis 11 of the vehicle and the axis of rotation 10 of the revolving turret 2. The convex cap 19 of the swivel bearing is carried by this pin 21 and itself supports the concave cap 18 of the swivel bearing. This concave cap 18 of the swivel bearing is in turn connected to the end of the piston of cylinder 13 by being inserted in a suitable bore therein with a press fit. If the position of the cylinder axis 13' is aligned with the concave cap 18 and the convex cap 19 of the swivel bearing, the axes 13' and 20 are perpendicular to each other. According to the association of the connections of the cylinder 13 at the turret and mount ends, the cylinder may have such a symmetrical position and retain it during its rising or extending movement. However, if two hydraulic cylinders 13a 13b are provided as an erecting device 6 for the mount 7, they are preferably arranged through a certain angle relative to the vertical plane including the longitudinal axis 11 of the vehicle and the swivel axis 10 of the revolving turret 2, whereby in FIG. 5a the axis 13' has a maximum lowered position relative to the axis of rotation 20 of the center bolt 21. During the rising or extending process of the piston rod 14, the angle between the axes l3 and 20 changes. This change is made possible in that the concave cap 18 on the convex surface of the cap 19 is swiveled round the axis at right angles to the plane defined in FIG. 50 by the axes 13 and 20 at the point of intersection of these axes.

We claim:

1. A mobile swivel aerial ladder comprising a support chassis having a longitudinal extending axis, a revolving turret pivotally mounted on said support chassis about an axis which is disposed perpendicularly to the longitudinal axis of said support chassis and said turret having a lower horizontal limiting plane, an extendible aerial ladder assembly having a base end located adjacent said turret and a top end disposed at the opposite end thereof, means for mounting said ladder assembly on said revolving turret for displacing said ladder assembly within a vertical plane through a range of working positions between a pair of angularly spaced terminal positions with one of the terminal positions disposed at a negative angle to the horizontal and the other terminal position disposed closely spaced from the vertical whereby from one terminal position said ladder can be pivoted through the horizontal position to the other terminal position, said means for mounting said ladder assembly comprising a mount member secured to the base end of said ladder assembly and pivotally attached to said turret for displacement angularly through a vertical plane, and at least one hydraulic cylinder assembly pivotally secured at one end to said turret member and pivotally secured at the other end to said mount member and said hydraulic cylinder assembly being extendible and retractable for angularly displacing said ladder assembly between its terminal positions and in the terminal position with said ladder assembly disposed at a negative angle to the horizontal the axis of said hydraulic cylinder assembly is arranged at a vertical angle upwardly from the lower horizontal limiting plane of said turret of between 30 to 50.

2. A mobile swivel aerial ladder as set forth in claim 1, wherein the center of pivotal attachment of said hydraulic cylinder assembly to said mount member is spaced between the axis of rotation of said mount member about said turret and the axis of rotation of said turret and the center of pivotal attachment of said hydraulic cylinder assembly to said turret is located above the lower limiting plane of said turret and on the opposite side of the axis of rotation of said turret from said mount member.

3. A mobile aerial ladder, as set forth in claim 2, wherein at least one end of said hydraulic cylinder assembly is connected to one of said mount member and turret by means of a ball and socket joint.

4. A mobile swivel aerial ladder, as set forth in claim 3, wherein said hydraulic cylinder assembly is connected to said mount by one said ball and socket joint, connector means for securing said ball and socket joint to said mount member comprising a box-shaped member having a base plate extending in the direction of the longitudinal axis of said chassis, a pair of spaced sidewalls extending substantially perpendicularly from said base plate and transversely of the longitudinal axis of said chassis and a receiving flange for said ball and socket joint spaced from said base plate and extending between the edges of said side plates remote from said base plate, said receiving flange positioned at an acute angle to said base plate and in the terminal position of said ladder assembly disposed at a negative angle to the horizontal said side plate located closer to said turret is shorter than the other said side plate.

5. A mobile swivel aerial ladder, as set forth in claim 4, wherein the acute angle of said receiving flange to said base plate is approximately 18.

6. A mobile swivel aerial ladder, as set forth in claim 2, comprising a swivel bearing, said swivel bearing comprising a concave cap and a convex cap, said concave cap secured to said hydraulic cylinder assembly, a bearing pin secured to said convex cap and extending transversely of the axis of said hydraulic cylinder assembly, said bearing pin pivotally mounted on one of said turret and said mount member.

7. A mobile swivel aerial ladder, as set forth in claim I, wherein said mount member comprises a boxlike structure formed of a plurality of plates welded together, in the terminal position of said. ladder assembly at the negative angle to the horizontal said hydraulic cylinder assembly has one end extending into the boxlike structure of said mount member, said plate of said mount member facing toward said turret having a recess formed in its lower edge for receiving said hydraulic cylinder assembly in the terminal position at the negative angle to the horizontal.

8. A mobile swivel aerial ladder, as set forth in claim 7, wherein said mount member has a pair of said plates forming the spaced sides thereof and extending in the longitudinal direction of said ladder assembly, another said plate extends transversely between said plates forming the sides and has the recess formed in its lower edge for receiving said hydraulic cylinder assembly in the terminal position at the negative angle to the horizontal, a further said plate forming the upper surface of said mount member and secured along two edges thereof to the pair of said plates forming the sides and along another edge to the another said plate forming the end of said mount member, a partition member secured at one edge to the another said plate at a position spaced below the further said plate and extending from the another said plate toward the axis of pivotal attachment of said mount member to said turret and secured to the lower surface of the further said plate so that said partition member is arranged at an acute angle to the further said plate, and in the terminal position at a negative angle to the horizontal said partition member is in substantially parallel relationship with the axis of said hydraulic cylinder assembly.

9. A mobile swivel aerial ladder, as set forth in claim 8, wherein the acute angle between said partition member and the further said plate is approximately 24.

10. A mobile swivel aerial ladder, as set forth in claim 8, wherein means secured to said mount member for supporting said mount member and ladder assembly on said turret when said mount member and ladder assembly are in the terminal position at the negative angle to the horizontal.

11. A mobile swivel aerial ladder, as set forth in claim 10, wherein said means for supporting said mount member and ladder assembly on said turret comprises a leg secured to each of said plates forming the sides of said mount member, each said leg projects outwardly from said plates forming the sides of said mount member for contacting said turret member when said mount member and ladder assembly are located in the terminal position at the negative angle to the horizontal, the lower end of each leg is beveled for affording contacting engagement with said turret over the dimension of said leg measured in the longitudinal direction of said mount member and ladder assembly.

12. A mobile swivel aerial ladder, as set forth in claim 1,

wherein a cage pivotally secured to the top end of said ladder assembly, said cage having a platform therein arranged to remain in the horizontal position as said ladder assembly is displaced between its terminal positions, and a mounting ladder movable attached to said cage for displacement into a position depending downwardly from the platform in said cage so that said mounting ladder can be used for climbing into said cage in the terminal position of said ladder assembly at the negative angle to the horizontal from a position below the platform in said cage. 

1. A mobile swivel aerial ladder comprising a support chassis having a longitudinal extending axis, a revolving turret pivotally mounted on said support chassis about an axis which is disposed perpendicularly to the longitudinal axis of said support chassis and said turret having a lower horizontal limiting plane, an extendible aerial ladder assembly having a base end located adjacent said turret and a top end disposed at the opposite end thereof, means for mounting said ladder assembly on said revolving turret for displacing said ladder assembly within a vertical plane through a range of working positions between a pair of angularly spaced terminal positions with one of the terminal position''s disposed at a negative angle to the horizontal and the other terminal position disposed closely spaced from the vertical whereby from one terminal position said ladder can be pivoted through the horizontal position to the other terminal position, said means for mounting said ladder assembly comprising a mount member secured to the base end of said ladder assembly and pivotally attached to said turret for displacement angularly through a vertical plane, and at least one hydraulic cylinder assembly pivotally secured at one end to said turret member and pivotally secured at the other end to said mount member and said hydraulic cylinder assembly being extendible and retractable for angularly displacing said ladder assembly between its terminal positions and in the terminal position with said ladder assembly disposed at a negative angle to the horizontal the axis of said hydraulic cylinder assembly is arranged at a vertical angle upwardly from the lower horizontal limiting plane of said turret of between 30* to 50*.
 2. A mobile swivel aerial ladder as set forth in claim 1, wherein the center of pivotal attachment of said hydraulic cylinder assembly to said mount member is spaced between the axis of rotation of said mount member about said turret and the axis of rotation of said turret and the center of pivotal attachment of said hydraulic cylinder assembly to said turret is located above the lower limiting plane of said turret and on the opposite side of the axis of rotation of said turret from said mount member.
 3. A mobile aerial ladder, as set forth in claim 2, wherein at least one end of said hydraulic cylinder assembly is connected to one of said mount member and turret by means of a ball and socket joint.
 4. A mobile swivel aerial ladder, as set forth in claim 3, wherein said hydraulic cylinder assembly is connected to said mount by one said ball and socket joint, connector means for securing said ball and socket joint to said mount member comprising a box-shaped member having a base plate extending in the direction of the longitudinal axis of said chassis, a pair of spaced sidewalls extending substantially perpendicularly from said base plate and transversely of the longitudinal axis of said chassis and a receiving flange for said ball and socket joint sPaced from said base plate and extending between the edges of said side plates remote from said base plate, said receiving flange positioned at an acute angle to said base plate and in the terminal position of said ladder assembly disposed at a negative angle to the horizontal said side plate located closer to said turret is shorter than the other said side plate.
 5. A mobile swivel aerial ladder, as set forth in claim 4, wherein the acute angle of said receiving flange to said base plate is approximately 18*.
 6. A mobile swivel aerial ladder, as set forth in claim 2, comprising a swivel bearing, said swivel bearing comprising a concave cap and a convex cap, said concave cap secured to said hydraulic cylinder assembly, a bearing pin secured to said convex cap and extending transversely of the axis of said hydraulic cylinder assembly, said bearing pin pivotally mounted on one of said turret and said mount member.
 7. A mobile swivel aerial ladder, as set forth in claim 1, wherein said mount member comprises a boxlike structure formed of a plurality of plates welded together, in the terminal position of said ladder assembly at the negative angle to the horizontal said hydraulic cylinder assembly has one end extending into the boxlike structure of said mount member, said plate of said mount member facing toward said turret having a recess formed in its lower edge for receiving said hydraulic cylinder assembly in the terminal position at the negative angle to the horizontal.
 8. A mobile swivel aerial ladder, as set forth in claim 7, wherein said mount member has a pair of said plates forming the spaced sides thereof and extending in the longitudinal direction of said ladder assembly, another said plate extends transversely between said plates forming the sides and has the recess formed in its lower edge for receiving said hydraulic cylinder assembly in the terminal position at the negative angle to the horizontal, a further said plate forming the upper surface of said mount member and secured along two edges thereof to the pair of said plates forming the sides and along another edge to the another said plate forming the end of said mount member, a partition member secured at one edge to the another said plate at a position spaced below the further said plate and extending from the another said plate toward the axis of pivotal attachment of said mount member to said turret and secured to the lower surface of the further said plate so that said partition member is arranged at an acute angle to the further said plate, and in the terminal position at a negative angle to the horizontal said partition member is in substantially parallel relationship with the axis of said hydraulic cylinder assembly.
 9. A mobile swivel aerial ladder, as set forth in claim 8, wherein the acute angle between said partition member and the further said plate is approximately 24*.
 10. A mobile swivel aerial ladder, as set forth in claim 8, wherein means secured to said mount member for supporting said mount member and ladder assembly on said turret when said mount member and ladder assembly are in the terminal position at the negative angle to the horizontal.
 11. A mobile swivel aerial ladder, as set forth in claim 10, wherein said means for supporting said mount member and ladder assembly on said turret comprises a leg secured to each of said plates forming the sides of said mount member, each said leg projects outwardly from said plates forming the sides of said mount member for contacting said turret member when said mount member and ladder assembly are located in the terminal position at the negative angle to the horizontal, the lower end of each leg is beveled for affording contacting engagement with said turret over the dimension of said leg measured in the longitudinal direction of said mount member and ladder assembly.
 12. A mobile swivel aerial ladder, as set forth in claim 1, wherein a cage pivotally secured to the top end of said ladder assembly, saId cage having a platform therein arranged to remain in the horizontal position as said ladder assembly is displaced between its terminal positions, and a mounting ladder movable attached to said cage for displacement into a position depending downwardly from the platform in said cage so that said mounting ladder can be used for climbing into said cage in the terminal position of said ladder assembly at the negative angle to the horizontal from a position below the platform in said cage. 